Driving on Blockhouse Bay Road a few days ago, I saw a symbol that I didn't understand on signs for the motorway. It is an upright light orange triangle with a white border on a green background. It is not a temporary warning sign, they are tilted squares with a black border, with a darker orange background. It is not a detour symbol, they are usually white with a black border, and the signs have been there for at least 3 years.

Here is a crop from Google maps, the image dated June 2021: